1. Field of the Invention
This invention relates to a DNA base sequence capable of increasing the amount of protein secreted by microorganisms and its derivative sequences; a recombinant plasmid including the whole or a part of said DNA base sequence; a method for preparing the recombinant plasmid; and a method of microbial breeding which comprises introducing the recombinant plasmid into a microorganism to increase the amount of protein secreted by the microorganism.
2. Description of the Prior Art
Some microorganisms (e.g., bacteria, yeasts and the like) secrete protein into the periplasm or out of the cells. Among others, bacteria of the genus Bacillus secrete a large amount of protein out of the cells.
From the viewpoint of microbial production of protein, it is of great significance to incorporate the genetic information involved in the promotion of protein secretion by such microorganisms into a host vector system according to genetic engineering techniques and thereby create a host vector system having the genetic information involved in the promotion of protein secretion. That is, the gene associated with high amounts of protein secretions can be expressed by forming such a host vector system within a microorganism. If the microorganism having amounts of protein secretions ability imparted thereto is grown, for example, in a culture medium, a large amount of protein is secreted into the culture medium. This protein can then be recovered from the culture medium according to a simple procedure.